In a stock pot, saute onion and garlic in 1 tbsp. oil for 5 minutes.Add 1 tbsp. oil and eggplant and stir-fry for 5 minutes.Add another tbsp. oil and the peppers and cook 5 minutes.Add the last tbsp. oil and the zucchini; cook for 5 more minutes.Then add seasonings and drained tomatoes;Cover and simmer for 30 minutes stirring occasionally.